Ted remembers enough about geometry to know that he needs to determine the shape of the entire pool before he can determine its area. However, the shape of this pool does not fit any of the shape definitions he learned. The pool has straight sides, rounded ends, and no points. It doesn't seem to be a square, rectangle, parallelogram, triangle, or circle. Then, Ted recalls that although there is no name for this shape, it does have a classification in geometry.

Ted's pool is an "unknown" figure. An unknown figure, in geometry, is any shape that does not fit a specific geometric definition. Look closely at the examples of known and unknown shapes shown below.